IttyBittyBitcoin is a set of free open-source cross-platform Java tools for working with bitcoin addresses. It allows for tinkering with every step of the address-creation process, so it's perfect for testing the different layers of Bitcoin's encryption. It can either be used as a library or run from the command line, and it is MIT-licensed. This means that you can use it anywhere for anything. IttyBittyBitcoin's only dependency is the BouncyCastle crypto library, which is used for some hashing.